1. Field of the Invention
The invention relates to a filter device and to a filter system for an exchange of gas between a fuel tank for liquid fuel and an environment.
2. Description of the Related Art
A fuel tank for liquid fuel in a motor vehicle is connected to an environment by a filter device. The tank customarily contains the liquid fuel and a volume of gas in which portions of the fuel are dissolved. Pressure in the fuel tank may rise due to heating, for example, because of solar insolation. Thus, the contents expand and the gas flows through the filter device and into the environment. The filter device is designed to retain at least a proportion of the fuel dissolved in the gas. For this purpose, a filter material for absorbing fuel is arranged in the filter device.
A tolerable concentration of fuel in the gas that escapes into the environment may vary when the filter device is used in different environments or in different motor vehicles. Regionally different limit values may also apply to the tolerable concentration.
U.S. Pat. No. 7,134,426 B2 discloses a filter device for treating fuel vapors. The filter device is filled partially with a granular filter material. A cartridge having a housing with further granular or monolithic filter material also can be used. The cartridge can be handled separately and can be exchanged at the filter device when the need arises.
U.S. Pat. No. 6,928,990 B2 discloses a further filter device for fuel vapors. This filter device has an encapsulated cartridge in which a filter material is arranged. The cartridge can be inserted into the filter device, and therefore fuel vapor from a tank flows through the cartridge.
The invention is based on the object of providing a filter device and a system that permit cost-effective and flexible filtering of fuel vapor.